Awnings are frequently installed on recreational vehicles, such awnings being frequently comprised of a fabric material affixed to the side of the vehicle and extending outward to a roller tube. The ends of the roller tube are held by brackets or arms pivoted to the side of the vehicle, to permit the roller tube to be moved between a closed position at which it is rolled on the roller tube and stored against the vehicle, and to one or more open positions at which is spaced from the vehicle to permit the fabric to serve as an awning.
When the roller tube is very long, for example at least 18 feet long, and especially when it is longer than 22 feet, flexing of the roller tube permits the center of the awning to sag, even though the fabric at the ends of the awning is held taut by the support brackets at the end of the tube. In order to avoid such sagging, adjustable tension rafters may be provided to extend between the vehicle and one or more intermediate positions of the roller tube. Such tension rafters are disclosed, for example, in U.S. Pat. Nos. 4,640,332 and 4,801,119.
The flexibility of a long roller tube also permits the awning to sag when the awning is in the closed position, i.e. rolled up on the roller tube and pivoted to lie against the side of the vehicle. For example, a 25 foot awning may sag as much as 21/2 inches at its center in this position. Such sagging is unsightly, and causes bouncing of the awning when the vehicle is moving. The bouncing distorts the fabric, and may result in a decrease in the life of the awning. It is therefore known to provide a support for the center of such an awning when it is in the closed position. Thus, U.S. Pat. No. 4,727,897 disclosed a structure dedicated to the support of the center of an awning only when it is in the closed position, and U.S. Pat. No. 4,801,119 discloses the use of the tension rafter, in an alternate position, for supporting the center of the awning during transport. In the arrangement of the latter reference, moving of the tension rafter to its alternate position requires separation of the rafter from its pivot coupling with the side of the vehicle, to abut the stored awning with the same cradle shaped rafter end that was used to abut the roller tube in the open position of the awning.
Typical pivot brackets for holding the ends of the roller tube include a rafter having one end pivoted to the side of the vehicle, and a main arm having one end releasably pivoted to the side of the vehicle below the rafter. The rafter and the arm are extensible, and their outer ends are pivotally held together generally at the axis of the roller tube. When the rafters and main arms are first pivoted away from the vehicle to move the awning from its closed position, the awning may assume a "neutral" position with the end rafters, as well as any central tension rafter, being sufficiently low that a person can easily adjust the lengths of these rafters to tension the fabric material. This position of the awning may be too low for practical use of the awning. The user may accordingly adjust the lengths of the main arms to raise the roller tube to a intermediate position at which normal living activities can occur under the awning. At this intermediate position the main brackets arms still extend between the roller arm and the side of the vehicle, thereby restricting passage at the ends of the awning. Accordingly, such awnings also have a higher "carport" position, attained by releasing the main arms from the vehicle and moving them to abut the ground immediately below the roller tube.
Movement of the awning between the various open positions has been found to affect the tension of the fabric such that, for example, a significant sag may appear at the center of the awning when it is moved to the carport position, even though it was adequately taut at the neutral position. This sagging results from the geometry of the awning structure, as well as movement or rotation of the roller tube when the height of the roller tube is changed. In the carport position the central tension rafter is generally too high to permit its length to the readily changed, so that it is frequently necessary to stand on a ladder to adjust the length of the rafter. This practice can be dangerous, especially to retired persons who frequently use mobile homes.
U.S. Patent application Ser. No. 216,835, Murray, filed Jul. 7, 1988 and assigned to the assignee of the present application, the contents of which are incorporated by reference herein, discloses an awning assembly wherein a fabric material extend between the vehicle and a roller, and is adapted to be wound on the roller in the closed position of the awning. Main arms are pivotally mounted to the ends of the roller, and are releasably held to the side of the vehicle. The lower ends of the main arms may thus be released from the vehicle to enable positioning of the awning in the carport position. Rafters are pivotally mounted to the vehicle. and are also pivotally coupled to the upper ends of the main arms. The pivotal coupling is configured to ensure that fabric is maintained taut when the awning is raised to its carport position, by shifting the position of the axis of the roller with respect to the ends of the rafters.